The invention relates to a method of soldering connection pins on carrier strips to printed circuit boards, notably to thick-film modules, the printed circuit boards being detachably arranged on the connection pins prior to soldering; and also relates to a dip soldering bath for performing this method.
Carrier strips with connection pins are well known and are industrially used. The carrier strips serve for the orderly and mechanized feeding of the individual connection pins to the relevant processing positions. Because the connection pins are normally fed to the processing positions by way of carrier strips provided on each end of the connection pins, the carrier strip provided near the connection tulip is removed before soldering, but the opposite carrier strip is removed only after the soldering of the connection pins.
Thick-film hybrid modules are the printed circuit boards which are most suitable for the use of such connection pins. In these modules, the conductor tracks extend very closely along the connection areas of the connection pins over a part of their length. This means that the soldering of the connection pins has to be extremely accurately performed. Furthermore, it is important that the bases of the connection pins adjacent the carrier strips exhibit as few solder bridges as possible after removal from the soldering bath, as the adjacent edge of the carrier strips acts as reference surface during its removal.
Thick-film hybrid modules comprising clamping connection pins are known to be dipped, together with the carrier strips extending from the bases of the connection pins, either individually or in small groups into the soldering bath in the upright position. However, solder bridging problems are then encountered.